1. Field of the Invention
The present invention relates generally to a Location Based Service (LB S) system, and more particularly, to an apparatus and method for switching modes in an LBS system based on Visible Light Communication (VLC).
2. Description of the Related Art
VLC refers to a wireless communication technology based on the light in a visible wavelength range, which performs wireless communication using visible radio waves. VLC is a communication scheme capable of replacing existing communication schemes based on Radio Frequency (RF), and intensive research thereon is now underway, which has coincided with the increased use of Light Emitting Diodes (LEDs). In common VLC, a transmitter sends visible light by using an LED or a Laser Diode (LD), color and illumination of which are controllable, as light sources, while a receiver processes the visible light using a Photo Detector (PD), thereby achieving VLC.
Utilization of VLC can be expanded to various existing RF-based services. An example may include Location Based Service (LBS) services that provide useful information to users considering the geographical locations where the users are currently located. LBS services may include public safety services, location tracking services, navigation services, information-providing services, etc., and in order to provide these LBS services, it is essential to identify the locations of users.
These services, which measure locations of users or terminals or obtains information about the locations, are called positioning services, for which media, such as radio waves and light, can be used. In the case of outdoor environments, a navigation system, which supports a positioning service using Global Positioning System (GPS) signals, can be considered the most typical LBS system. The GPS signals, however, occasionally may not be received in indoor environments, whereas VLC can be used even in indoor environments where the use of RF is limited. With the growth of skyscrapers, underground malls and large shopping malls, the positioning service needs to be provided in these indoor environments.
To furnish a VLC-based LBS system in the indoor environments described above, how to configure lighting devices and terminals is important. In an LBS system using lighting infrastructure, several service scenarios may exist depending on configurations of the lighting devices and the terminals. For example, VLC between a lighting device capable of supporting only transmission and a terminal capable of supporting both transmission and reception is inefficient. Even though the lighting device can support only transmission, the terminal sends a request for location information to the lighting device. In this case, it is preferable that after recognizing that the lighting device can support only transmission, the terminal inactivates (disables) a transmit mode and operates only in a receive mode. Therefore, it is necessary to define service modes fitting several possible service scenarios according to the transmission/reception availability of the lighting device, the transmission/reception availability of the terminal, and the use/nonuse of the existing RF communication.